Orange Crush 35RT no dirty channel

[Randall]

Cannot find a schematic for this. Came in with the panel clean/dirty switch doing nothing, stuck on clean. The toggle appears to be switching something to ground, which it seems to be doing at the switch, but I cannot see what it is connected to on the other side of the board. After that, the trail goes dim.

How to approach this?

[The Dude]

I don't have a schematic, but have you tried it with a footswitch? If so, does it work with the footswitch? Sans schematic, the first thing I would do is clean the footswitch jack and run a plug in and out a few times. In many amps, the footswitch jack is a switching jack that disables the front panel switch when a footswitch is plugged in. If it's not working, the amp thinks there is a footswitch attached.